Effects of hydrostatic pressure on mechanical behaviour and deformation processing of materials

The processing and subsequent mechanical behaviour of a variety of commerci ally important materials are affected by the imposed stress state. In this review, the experimentally documented effects of superimposed pressure on d eformation under quasistatic conditions are summarised, followed by a prese ntation of the effects of superimposed pressure on the fracture behaviour o f a variety of materials including both ductile and brittle systems. It is shown that the pressure responses of a variety of materials show distinct d ifferences and the potential reasons for these differences are presented. F inally, in the light of all of these observations, the effects of changes i n stress state on deformation processing are reviewed. In particular, the e volution of hydrostatic stresses during various forming operations is cover ed followed by a review of published work and the potential benefits of sup erimposing pressure during processing of a variety of materials. IMR/328. ( C) 1998 The Institute of Materials and ASM International.